The present invention relates generally to systems for spreading particulate material. More specifically, the present invention relates to a vehicle-mounted spreader for distributing particulate material such as sand or salt onto a surface in an even manner while the vehicle is in motion across the surface.
Trucks are often used to spread various materials on road surfaces during inclement weather. For example, dump trucks often include a storage bin for carrying particulate material such as salt or sand and a spreader for distributing the particulate material onto the surface of a road during snow and ice storms. When such a truck is in motion on a highway or other road surface, the particulate material flows from the storage bin into the spreader, and is then distributed by the spreader behind the truck for deposit onto the surface of the road. The material so distributed improves the traction on the road for other vehicles.
Although many arrangements for such vehicle-mounted spreaders are known, most share common deficiencies. In many cases, the material being spread is ejected from the back of the truck at a constant velocity independent of the speed of the vehicle with respect to the ground, and the material is not spread in a direction opposite to that of the vehicle. This typically causes the material to impact the road surface with a nonzero velocity, with the material xe2x80x9crollingxe2x80x9d across the road surface. This can result in an uneven distribution of material on the road and can cause certain areas of the surface to be not covered at all. In the case of icy road conditions, not having an even distribution of material will mean that certain areas of the road will not be sanded or salted, therein creating hazardous road conditions for drivers or pedestrians. Further, when the material is spread unevenly across the road surface, some of the material will often travel to the sides of the road where cars and pedestrians do not typically travel. The material that lands on the side of the road will therefore be wasted, and can also lead to excessive environmental damage to plants or other objects adjacent to the road.
There have been attempts to create zero velocity spreaders that perform an adequate job of evenly distributing particulate material. For example, U.S. Pat. No. 5,842,649 to Beck et al, discloses a conveyor arrangement with a rotary spinner, wherein the spinner rotates about an axis which is substantially perpendicular to the ground. Because a typical spinner is inclined to discharge material in all 360 degrees, a shroud is strategically placed around the spinner in the directions in which it is undesirable to have material discharged. A conveyor brings the material into the spinner, which is located between two and fourteen inches from the ground, and the spinner then propels the granular material out of a discharge spout located directly behind the spinner. A control system monitors and adjusts the speed of the conveyor and spinner in order to have the material exit the discharge spout at substantially the same speed and in the opposite direction as the vehicle""s motion. This arrangement has several drawbacks, however. Because the spinner is oriented with its axis of rotation perpendicular to the ground, material is forced through the spinner in a plane substantially parallel to the ground before the material is forced into the discharge spout. This action is inefficient in that the centripetal force of the material as it travels through the spinner acts to force the material against the outer shroud instead of in a direction close to the entrance point of the discharge spout. Since the spinner is therefore required to work harder, the motor powering the spinner must provide more energy in order to have the material exit at the appropriate speed. Additionally, the horizontal spinner causes the material to be ejected into the discharge spout with a side-to-side motion relative to the direction of the vehicle, which will cause some material to impact upon the side walls of the discharge spout and also cause some lateral motion in the material as it leaves the spout. This will result in some lateral spreading of the material across the road, which is undesirable from a zero velocity spreader. Furthermore, the material guide needs to be located less than 24 inches from the ground and preferably from 2 to 14 inches from the ground surface in order to minimize the width of the path of particulate material being deposited. Finally, it is also difficult to monitor whether the material exits the discharge spout at substantially zero velocity relative to the road due to the multiple directions in which the material is being forced through the spinner.
There are other vehicle-mounted spreaders on the market which use a forced flow of air to eject materials from the back of the vehicle at zero velocity relative to the ground. Such spreaders also have their drawbacks, however. For example, the components used by such spreaders to generate the airflow which forces the material out of a discharge spout require a large amount of energy to create an airflow sufficiently strong to carry the relatively heavy granular material, such as rock salt or sand. For example, some spreaders currently being marketed require up to 25 horsepower in order to operate the spreader when the vehicle is traveling at under 30 miles per hour. Also, controlling the flow of air accurately enough to maintain a zero velocity spreading of the materials can be difficult. Air-driven spreaders also have the problem that it is difficult to accurately control the direction and speed that the materials are ejected from the vehicle. Finally, such systems are difficult to retrofit to existing vehicles such as pickup or dump trucks.
Thus, it would be advantageous to provide an improved vehicle-mounted spreader for depositing materials onto a road surface at a substantially-zero velocity relative to the road. It would also be advantageous to provide such a system wherein both the direction and the velocity of the materials being ejected can be accurately controlled so as not to result in any unwanted spreading of the material across the surface. Further, it would be advantageous to provide such a system that requires a minimum amount of energy to control the components required for spreading the materials. It would also be advantageous to provide a system for spreading granular materials at zero velocity that can be easily installed or retrofitted on a preexisting vehicle, such as a pickup truck or a dump truck.
In accordance with one embodiment of the present invention, a vehicle-mounted spreader for distributing material onto a surface while the vehicle is in motion across the surface includes a discharge spout, a rotor coupled to the discharge spout, a rotor motor coupled to the rotor, a conveyor coupled to the rotor, and a conveyor motor coupled to the conveyor. The discharge spout is located at the back of the vehicle for directing the material being distributed onto the road surface. The rotor is used to propel the material into the discharge spout. The rotor has an axis of rotation substantially parallel to the surface of the road, and is powered by the rotor motor. The conveyor, preferably in the form of an auger, is used to transport the material in specific metered amounts from a storage bin supported by the vehicle to the rotor. This conveyer is preferably powered by the conveyor motor. The rotor motor and conveyor motor are preferably hydraulically driven, and can be controlled independently of each other to provide the user with greater control over the system.
The discharge spout, which is located aft of the rotor, is oriented so as to direct the materials in a direction substantially opposite to that in which the vehicle is moving. In one embodiment of the invention, the discharge spout has an entrance or inlet opening, an exit or outlet opening and a bend or middle portion therebetween. The entrance is located directly below the location at which material exits from the rotor. The bend in the spout then alters the direction of the material so the material exiting the spout will be traveling substantially opposite the direction of the vehicle.
The spreader also includes an electronic control system for monitoring and adjusting the flow of material as it exits the vehicle. The control system includes an electronic control box. An electronic speedometer, often already provided on currently existing vehicles, provides a signal to the control box, informing it of the present vehicle speed. The control box also receives signals from the conveyer motor and/or the rotor motor indicating the rotational speeds of each motor. Alternatively, the control box can receive the signals directly from the conveyer and/or the auger representing the respective velocities. The control box also provides valve control signals to solenoid-operated electrohydraulic valves. These valves provide a controlled flow of pressurized hydraulic fluid to the conveyor and rotor motors in response to the above-mentioned valve control signals. The result of this closed loop system is that the control box provides control over the conveyer and rotor speeds by monitoring the vehicle ground speed, the conveyor motor speed and the rotor motor speed as inputs. Additionally, the hydraulics for this system will preferably require less horsepower to operate at speeds near 30 miles per hour when compared to units that use air. In another embodiment of the invention, the conveyor motor and rotor motor also include rotational speed sensors to provide feedback signals to the control box indicating the motor speeds of each.
In one embodiment, the system also includes a manual on/off switch located within the vehicle cab to give the operator additional control over the flow of the material (i.e., turning the flow on and off). Further, the spreader can include a manually-operated controller within the cab so that the operator can manually adjust the amount of material being transported by the conveyer and discharged by the rotor.
Additionally, the system may include a xe2x80x9cwet kit optionxe2x80x9d that is commonly known in the art such that the system can operate while transporting and distributing materials such as brine.
These and other objects, advantages and features of the invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description taken in conjunction with the accompanying drawings wherein like elements have like characters throughout the drawings.